The present invention relates to improved apparatus for supporting phonographic tone arms, and more particularly relates to improvement in the supporting structure for phonographic tone arms on phonographic disc players of the linear tracking type.
One conventional supporting structure of the linear tracking type is provided with a carriage movable on and along a tract in a direction normal to the radial direction of the turntable, the track being arranged below the bottom of the player board. The tone arm and its related parts are supported by the carriage by way of a connecting rod which extends rearwardly, bends and extends downwardly on the back side of the player board, again bends and extends forwardly through a horizontal slit formed in the back of the player board and is coupled to the top of the carriage via a bearing. This structure may serve for enhancement of the outside design of the disc player as the slit for passage of the connecting rod is provided on the back side of the player board, i.e. at a position almost invisible to the user. However, the complicated curved construction of the connecting rod tends to cause undesirable distortion of the connecting rod against the bearing surface and this distortion may lead to relatively quick wearing-out of the bearing. Such wearing-out of the bearing and its related parts results in disorder in the lateral balance of the tone arm and its related parts. In addition, the relatively high position of the center of gravity of the tone arm and its related parts with respect to the carriage may lead to unstable posture and movement of the carriage on and along the track. Thus, the ability of the supporting structure for minimizing undesirable distortion and pressure on the stylus tip is lowered.
In another conventional supporting structure of the linear tracking type, a carriage moves on and along a track in a direction normal to the radial direction of the turntable, the track being arranged below the bottom of the player board. The tone arm and its related parts are supported by the carriage by way of a straight vertical connecting rod which extends rearwardly through a horizontal slit formed in the top wall of the player board and coupled to the carriage. Although this structure is free of the trouble caused by the distortion of the connecting rod, presence of the slit in the top wall of the player board degrades the outside design of the disc player and allows easy egress of dust and other extraneous matter into the interior of the disc player. Further, even in the case of this supporting structure, the position of the center of gravity of the tone arm and its related parts is still relatively high with respect to the position of the carriage.